Gas discharge patterns in a large jetting fluidized bed with a vertical nozzle

The gas discharge patterns, a jet and a spout, generated by a vertical nozz le in an 8-m-high, 0.5-m-diameter jetting fluidized bed were investigated u sing frame-by-frame analysis and Sth VCD software analysis. The static bed height was varied from 0.38 to 0.66 m, and the nozzle jet velocity was vari ed from 16.1 to 64.26 m/s. A correlation was developed using experimental d ata to predict the transition of the flow pattern from a jet to a spout. Th e study shows that the major frequency in the power spectrum density functi on agrees with the jet collapse frequency measured by frame-by-frame analys is and Sth VCD software analysis. The major frequency in the power spectrum density function increases with increasing jet gas velocity. In addition, the jet velocity at the critical point in the curve of the major frequency versus the jet gas velocity corresponds to the gas velocity for the transit ion from a jet to a spout.